Delineating biomonitoring potential of two crustose lichens Bacidia convexula and B. submedialis through elemental accumulation and microstructural parameters

Gupta V., Gupta N., Nayaka S. & Lavania S.
2024: 1-15
Lichens possess unique characteristics, relying on a protective cortex and a filtration mechanism for absorption in the absence of roots, enabling efficient mineral nutrition. However, this distinctive feature also renders them susceptible to accumulating airborne pollutants, particularly metal, beyond optimal levels. The current investigation focuses on elemental accumulation in two crustose lichen species, namely Bacidia convexula and B. submedialis, aiming to highlight their potential as biomonitoring tools and assess the impact of anthropogenic activities, disturbed environment surrounding brick-kilns as an illustrative example. Microstructural changes, surface sorption and fibrous deposition of elemental ions were scrutinized through the application of SEM-EDX microscopy and advanced analytical techniques such as ICP-MS and FTIR. The SEM images unveiled alterations in the lichen's microstructure, entrapment of gas bubbles as well as fibrous deposition and surface sorption of elemental ions. The highest mean concentration of Ag (0.36 +/- 0.01), Al (1194.87 +/- 67.6), As (0.6 +/- 0.02), Cd (0.29 +/- 0.01), Cr (107.79 +/- 0.39), Cu (17.12 +/- 0.07), Fe (1722.73 +/- 8.48), Mg (1995.13 +/- 31.28), Mn (235.06 +/- 0.67), Ni (9.09 +/- 0.05), and Zn (87.63 +/- 0.84 mg kg(-1)) were estimated in the thalli of B. submedialis, whereas B. convexula accumulated highest concentration of Co (1.34 +/- 0.02), Li (3.67 +/- 0.35), Pb (11.92 +/- 0.13), and Se (0.27 +/- 0.01 mg kg(-1)). In both the lichens, FTIR analysis identified the functional groups such as, alcohol (O-H), alkenes (C-H), alkyl halides (C-Br), aromatic (C = C), methoxy (O-CH3) and octahedral groups (AlO8). The analytical results of EDX showed a higher weight of O with 46.11%, Mg (0.43%), Al (0.9%), Fe (0.38%), Si (1.62%), Zr (1.67%) in B. submedialis. Whereas, B. convexula revealed higher weight of C with 62.36% and Ca (0.62%). As such differential response was observed to metal ion stress, showing B. submedialis to be more tolerant than B. convexula. The information generated could be used as biomonitoring indicator of air quality and pollution. Air pollution, Lichen biomonitoring, Ecosystem health, Heavy metal, Lichenized fungi, HEAVY-METAL ACCUMULATION, AIR-POLLUTION, PHYSIOLOGICAL ATTRIBUTES, PHAEOPHYSCIA-HISPIDULA, ATMOSPHERIC-POLLUTION, CALOPLACA-AURANTIA, EPIPHYTIC LICHENS, TRACE-ELEMENTS, DIVERSITY, URBAN
Tuesday, 09 April 2024 14:40